Journal bearings, especially those used underwater as in deep well pump shafts or in the outboard bearings of propeller shafts in ships, have been made for many years with a rubber surface divided by longitudinal grooves or spaces, since it has been found that smooth rubber lubricated with water has a very low coefficient of friction under the proper operating conditions so that no special provision for supply of lubricant is required. Such bearings have sometimes given excellent service for prolonged periods with almost no wear, but in other instances, not easily distinguishable, have been less satisfactory and have exhibited rapid and sometimes erratic wear. In some instances with limited power, the water has been squeezed out of the bearing when the shaft is stationary so that the extremely high coefficient of friction of dry rubber has actually prevented starting of rotation.